Stand up pen



FIG. 1 is a top, side perspective view of a stand up pen, showing my new design;

FIG. 2 is a right end elevational view thereof;

FIG. 3 is a left end elevation view thereof;

FIG. 4 is a front elevational view, rotated 45 degrees forward relative to FIG. 1, the rear elevational view being a mirror image to the front elevational view;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a stand up pen, as shown and described. 